Simple method for measuring the linewidth enhancement factor of semiconductor lasers.

Area of Science:

• Optoelectronics
• Laser Physics
• Semiconductor Devices

Background:

• Semiconductor lasers (SLs) are crucial optoelectronic components.
• Accurate measurement of the linewidth enhancement factor (LEF) is vital for SL performance.
• Existing LEF measurement methods can be complex.

Purpose of the Study:

• To propose and demonstrate a simple method for measuring the LEF of SLs.
• To utilize the self-mixing effect in SLs for LEF determination.
• To provide an experimentally verified and computationally supported technique.

Main Methods:

• Employing the self-mixing effect where optical feedback modulates SL output power.
• Analyzing the relationship between light phase and power using Lang and Kobayashi equations.
• Measuring LEF from the overlapped power values of two SLs under varying optical feedback strengths.

Main Results:

• A straightforward LEF measurement technique based on optical feedback is developed.
• The modulated envelope shape of SL output power is shown to depend on optical feedback and LEF.
• LEF can be determined by comparing SL power outputs at two distinct optical feedback levels.

Conclusions:

• The proposed method offers a simple and effective way to measure SL LEF.
• The technique is validated through both numerical simulations and experimental implementations.
• This work contributes a practical tool for characterizing semiconductor lasers.